[PATCH v2 2/2] realtek: use assisted learning on CPU port

[Jan Hoffmann]

On 26.10.22 at 00:20, Jan Hoffmann wrote:
> L2 learning on the CPU port is currently not consistently configured and
> relies on the default configuration of the device. On RTL83xx, it is
> disabled for packets transmitted with a TX header, as hardware learning
> corrupts the forwarding table otherwise. As a result, unneeded flooding
> of traffic for the CPU port can already happen on some devices now. It
> is also likely that similar issues exist on RTL93xx, which doesn't have
> a field to disable learning in the TX header.
> 
> To address this, disable hardware learning for the CPU port globally on
> all devices. Instead, enable assisted learning to let DSA write FDB
> entries to the switch.
> 
> For now, this does not sync local/bridge entries to the switch. However,
> support for that was added in Linux 5.14, so the next switch to a newer
> kernel version is going to fix this.
> 
> Signed-off-by: Jan Hoffmann <jan at 3e8.eu>
> ---
>   .../files-5.10/drivers/net/dsa/rtl83xx/dsa.c     | 16 ++++++++++++++++
>   .../files-5.10/drivers/net/dsa/rtl83xx/rtl838x.h |  6 ++++++
>   2 files changed, 22 insertions(+)
> 
> diff --git a/target/linux/realtek/files-5.10/drivers/net/dsa/rtl83xx/dsa.c b/target/linux/realtek/files-5.10/drivers/net/dsa/rtl83xx/dsa.c
> index 474d540945d1..319f171eaacc 100644
> --- a/target/linux/realtek/files-5.10/drivers/net/dsa/rtl83xx/dsa.c
> +++ b/target/linux/realtek/files-5.10/drivers/net/dsa/rtl83xx/dsa.c
> @@ -162,6 +162,16 @@ static void rtl83xx_setup_bpdu_traps(struct rtl838x_switch_priv *priv)
>   		priv->r->set_receive_management_action(i, BPDU, COPY2CPU);
>   }
>   
> +static void rtl83xx_port_set_salrn(struct rtl838x_switch_priv *priv,
> +				   int port, bool enable)
> +{
> +	int shift = SALRN_PORT_SHIFT(port);
> +	int val = enable ? SALRN_MODE_HARDWARE : SALRN_MODE_DISABLED;

While looking at the patch again, I noticed that the type of these 
variables should probably be u32 (to avoid possible undefined behaviour 
when shift is 30).

As the patch is already accepted now, I'll send a separate fix.

> +
> +	sw_w32_mask(SALRN_MODE_MASK << shift, val << shift,
> +		    priv->r->l2_port_new_salrn(port));
> +}
> +
>   static int rtl83xx_setup(struct dsa_switch *ds)
>   {
>   	int i;
> @@ -205,6 +215,9 @@ static int rtl83xx_setup(struct dsa_switch *ds)
>   
>   	priv->r->l2_learning_setup();
>   
> +	rtl83xx_port_set_salrn(priv, priv->cpu_port, false);
> +	ds->assisted_learning_on_cpu_port = true;
> +
>   	/*
>   	 *  Make sure all frames sent to the switch's MAC are trapped to the CPU-port
>   	 *  0: FWD, 1: DROP, 2: TRAP2CPU
> @@ -263,6 +276,9 @@ static int rtl93xx_setup(struct dsa_switch *ds)
>   
>   	priv->r->l2_learning_setup();
>   
> +	rtl83xx_port_set_salrn(priv, priv->cpu_port, false);
> +	ds->assisted_learning_on_cpu_port = true;
> +
>   	rtl83xx_enable_phy_polling(priv);
>   
>   	priv->r->pie_init(priv);
> diff --git a/target/linux/realtek/files-5.10/drivers/net/dsa/rtl83xx/rtl838x.h b/target/linux/realtek/files-5.10/drivers/net/dsa/rtl83xx/rtl838x.h
> index e2b82a4975f0..10913dacef42 100644
> --- a/target/linux/realtek/files-5.10/drivers/net/dsa/rtl83xx/rtl838x.h
> +++ b/target/linux/realtek/files-5.10/drivers/net/dsa/rtl83xx/rtl838x.h
> @@ -245,6 +245,12 @@
>   #define RTL839X_L2_PORT_NEW_SALRN(p)		(0x38F0 + (((p >> 4) << 2)))
>   #define RTL930X_L2_PORT_SALRN(p)		(0x8FEC + (((p >> 4) << 2)))
>   #define RTL931X_L2_PORT_NEW_SALRN(p)		(0xC820 + (((p >> 4) << 2)))
> +
> +#define SALRN_PORT_SHIFT(p)			((p % 16) * 2)
> +#define SALRN_MODE_MASK				0x3
> +#define SALRN_MODE_HARDWARE			0
> +#define SALRN_MODE_DISABLED			2
> +
>   #define RTL838X_L2_PORT_NEW_SA_FWD(p)		(0x3294 + (((p >> 4) << 2)))
>   #define RTL839X_L2_PORT_NEW_SA_FWD(p)		(0x3900 + (((p >> 4) << 2)))
>   #define RTL930X_L2_PORT_NEW_SA_FWD(p)		(0x8FF4 + (((p / 10) << 2)))